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View Full Version : Always on 'Clean boost' pedal/buffer VS turning the amp up! Myth? Pointless?


robojim4000
08-14-2011, 04:04 PM
But surely for those of us that play in a band and have limitations on the audible volume of the amp, wouldn't this just mean volume down has to be turned down on the amp as a result (particularly non- master volume maps)

So whats the point? Not being able to crank the amp as much is a BAD thing right?

In other words, for example, isn't....

Clean boost+amp at '4' = no clean boost+amp at '5' = pointless?

Not to mention $200 pedals that 'bring back the highs' after signal loss??? just turn the treble up!?!

sdd17
08-14-2011, 04:09 PM
I would say a buffer pedal to bring the signal as close to straight in is the best deal if there is degradation.
I think the boost verses amp volume can be pointless yes.

shredtrash
08-14-2011, 04:47 PM
I would say a buffer pedal to bring the signal as close to straight in is the best deal if there is degradation.
I think the boost verses amp volume can be pointless yes.

Not pointless. Balancing preamp and poweramp gain with some type of booster is one of the biggest pro tricks in the book. Just cranking an amp usually doesn't work the way you would think.

robojim4000
08-14-2011, 04:57 PM
Not pointless. Balancing preamp and poweramp gain with some type of booster is one of the biggest pro tricks in the book. Just cranking an amp usually doesn't work the way you would think.

maybe, but I struggle to get either the pre-amp OR the power amp cooking on my 15 watt amp at lowish volumes. In theory on a master volume amp a boost pedal would drive the preamp harder (and overall volume would be controlled with the master volume), but on a non-MV amp a boost pedal just makes things louder - that doesn't help me at all in terms on getting a better tone at controllable volumes

scr@tchy
08-14-2011, 05:41 PM
Unless I am not understanding the question, where this works for me is when I can get the amp to be just at break up with my guitar's volume at full. Then it it with the boost and the volume increase isn't so dramatic.

L_Totti
08-14-2011, 05:44 PM
Not pointless. Balancing preamp and poweramp gain with some type of booster is one of the biggest pro tricks in the book. Just cranking an amp usually doesn't work the way you would think.


This.

teleclem
08-14-2011, 06:02 PM
Fwiw, to my ears, amp w/treble up & amp w/ buffer sound pretty different.

sdd17
08-14-2011, 06:12 PM
to the OP
are you referring to a non-master amp?

shredtrash
08-14-2011, 06:49 PM
maybe, but I struggle to get either the pre-amp OR the power amp cooking on my 15 watt amp at lowish volumes. In theory on a master volume amp a boost pedal would drive the preamp harder (and overall volume would be controlled with the master volume), but on a non-MV amp a boost pedal just makes things louder - that doesn't help me at all in terms on getting a better tone at controllable volumes

A booster works the same way whether the amp is a MV or non-MV amp. However, a non-MV amp will have less "volume control" capability. You either need to get an attenuator or get another amp that fits your application better.

FenderBigot
08-14-2011, 07:10 PM
I dunno... while I hear what you're saying in the OP, I'm not sure I can support it. My EP Booster does something special to the sound of the amp clean. I also think my two primary OD pedals (Amp11 and DLS) both sound better with their volume up, so to get the same volume clean as I do dirty, I use the EP Booster.

Blues Lyne
08-14-2011, 07:29 PM
In most, probably all, tube guitar amps there are tube gain stages before the volume control. Those tube stages will react different depending on the amount of signal feeding them. Using a boost to push those stages, even if the volume is then turned down to compensate, will change the how the amp sounds and/or reacts to your playing. Depending on the amp and the amount of boost, this will result in fattening the tone, and/or some compressions, and/or pushing the tubes into saturation (breakup). I have a '61 Tweed Gibson Falcon. It loves some boost before it, even if I'm going for clean tones. It just sounds fatter and more solid and punchy. While a boost can be used to overdrive an amp, it can also be used to maximize the signal levels and get proper gain staging from the amp.

mmolteratx
08-14-2011, 07:31 PM
Regardless of settings, if you're getting the same volume, you're power tubes are getting the same signal at the grid.

schwa
08-14-2011, 07:48 PM
maybe, but I struggle to get either the pre-amp OR the power amp cooking on my 15 watt amp at lowish volumes. In theory on a master volume amp a boost pedal would drive the preamp harder (and overall volume would be controlled with the master volume), but on a non-MV amp a boost pedal just makes things louder - that doesn't help me at all in terms on getting a better tone at controllable volumes

You're using the boost wrong. It doesn't work at low volumes. For your application, you want an OD pedal. Set the volume at unity (or a small boost), and use the drive knob to add the grit you aren't getting with the amp volume low.

On a NMV amp they only get louder above 5 or so. After that they just add more distortion. Even so with the volume cranked, it's not super gainy. Add a boost to a cranked amp, and it puts things over the top - adding gain and potentially some cool transistor/eq magic as well.

jtaylor996
08-15-2011, 09:49 AM
Regardless of settings, if you're getting the same volume, you're power tubes are getting the same signal at the grid.

That blanket statement is way to simplistic for a huge variety of amps out there. There's post phase inverter master volumes, output transformer sagging, VVR power scaling, attenuators, etc, etc, etc... A lot of this stuff happens in the best amps out there, too.

Cirrus
08-15-2011, 09:56 AM
Regardless of settings, if you're getting the same volume, you're power tubes are getting the same signal at the grid.

No, I am not power tubes!

the ruckus
08-15-2011, 10:57 AM
For me volume on a tube amp provides more than just "loudness", it's about soft compression, EQ difference, push back, break up & a dozen other little things. With lots of pedals between my guitar & amp some of this lost. A good buffer or responsive boost helps restore many of these factors & bring back the feel. I think most newer players have little to no experience plugging a quality guitar straight into a quality amp & really playing thru it to learn how it feels. Buffers aren't about making you louder but helping restore the feel of straight in.

sdd17
08-15-2011, 11:09 AM
Put your amp at a level that is right before breakup and hit a chord or 2 and listen.
Now plug in a quality clean boost pedal like a creation audio 4.23 in and set the level of the pedal at about 10 o'clock. dial your amp back to match the volume you had when you plugged straight in.

Should sound pretty close.

That being said the perhaps it is a better option to just run the amp hotter.

I think this may reflect the original OP's question.

semi-hollowbody
08-15-2011, 11:32 AM
If I run a barber launch pad LAST in my chain (as a clean boost) I can get my amp (drri) right on the verge of breakup without cranking the amp...

My drri by itself starts to break up with humbuckers at 4 1/2-5 on the volume...WAY too loud for home play...but with the barber launch pad, I turn the amp to between 1 and 2, volume-wise it is closer to 2 1/3-3, and its right on the edge of break up

freaksho
08-15-2011, 11:39 AM
In most, probably all, tube guitar amps there are tube gain stages before the volume control. Those tube stages will react different depending on the amount of signal feeding them. Using a boost to push those stages, even if the volume is then turned down to compensate, will change the how the amp sounds and/or reacts to your playing. Depending on the amp and the amount of boost, this will result in fattening the tone, and/or some compressions, and/or pushing the tubes into saturation (breakup). I have a '61 Tweed Gibson Falcon. It loves some boost before it, even if I'm going for clean tones. It just sounds fatter and more solid and punchy. While a boost can be used to overdrive an amp, it can also be used to maximize the signal levels and get proper gain staging from the amp.

Put your amp at a level that is right before breakup and hit a chord or 2 and listen.
Now plug in a quality clean boost pedal like a creation audio 4.23 in and set the level of the pedal at about 10 o'clock. dial your amp back to match the volume you had when you plugged straight in.

Should sound pretty close.

That being said the perhaps it is a better option to just run the amp hotter.

I think this may reflect the original OP's question.

i think these two posts get to the core of what the OP is asking, and i think Blues Lyne's reponse is closer to my understaning. that is, some gain stage(s) in nmv amps occur before volume control so if you hit those harder (a clean boost) then you'll get saturation/compression/etc from the preamp and that will remain if you turn down the amp's volume.

in light of this i think i might disagree with sdd17's description as the effect of the boost will still be heard even when you turn down the amp's volume. the one unknown is that 10:00 setting you talk about, which might still be unity gain (or less) and therefore you may be right and there will be little effect (and this may be what the OP is asking about).

mds
08-15-2011, 11:46 AM
I run a CAE Boost/Buffer at the beginning of my pedal board and just barely push the level up. It doesn't really change the gain on the amp, it just keep my signal strong through my pedalboard and the long run back to the amp. It makes a big difference in my tone.

jogden
08-15-2011, 11:54 AM
I've been using an Xotic EP Booster. Though not exactly a "clean boost" it comes close. As one friend described it, it takes my guitar tone from sounding like a 12 band EQ to a 32 band EQ. Especially at lower volumes it is priceless for increasing quality of sound. This has been the single best pedal investment I have ever made. I leave it always on. Doesn't necessarily push things harder, it just pushes the dynamic -- maybe in line with what others have said about the pre-amp tubes vs. power tubes.

In the end I think there is a distinct difference - so far as my rig is concerned.

sdd17
08-15-2011, 11:54 AM
[QUOTE=

in light of this i think i might disagree with sdd17's description as the effect of the boost will still be heard even when you turn down the amp's volume. the one unknown is that 10:00 setting you talk about, which might still be unity gain (or less) and therefore you may be right and there will be little effect (and this may be what the OP is asking about).[/QUOTE]

10 o'clock on the creation audio is about 5 db boost give or take
so its not a trying to push the front end of an amp into saturation kind of boost.

To my ears there is no discernible difference sonically between that kind of processing vrs straight in.

Now a more significant boost is a different story.

Just trying to address the OP
Not sure if this does or not
maybe he can chime in

freaksho
08-15-2011, 12:04 PM
10 o'clock on the creation audio is about 5 db boost give or take
so its not a trying to push the front end of an amp into saturation kind of boost.

To my ears there is no discernible difference sonically between that kind of processing vrs straight in.

Now a more significant boost is a different story.

Just trying to address the OP
Not sure if this does or not
maybe he can chime in

yeah, ok. i see. but only if there is a good amount of headroom left in the preamp, no? if otth the amp is set right on the edge of breakup then that 5dB would probably push it into saturation, no? would that grit still be heard even if you turn down the amp?

this is a question i've always wondered: which stages are controlled by the volume knob on nmv amps, and which tubes distort when breakup starts - all of them equally? i have one nmv amp (5E3) and i know i get breakup much earlier on the volume knob when i use an HB guitar than SC, so i use the low input to reduce the signal to the preamp. now what i can't tell is whether the breakup still occurs at the same actual volume once i turn it up from there (hard to tell without a sound level meter or something).

Braunzo
08-15-2011, 12:31 PM
No, I am not power tubes!

I guess I am the only one that appreciated this... :rotflmao

hustist1
08-15-2011, 01:22 PM
this is a question i've always wondered: which stages are controlled by the volume knob on nmv amps, and which tubes distort when breakup starts - all of them equally?

This depends on the amp.

In a Fender blackface, for instance, (that is, the AB763 schematic) the input goes to the first gain stage, through the tone stack (BIG gain loss; what a passive tone stack does is send specific parts of your signal to ground); then through the volume control. Then it goes through a recovery gain stage (to make up for the gain lost by the tone stack) and possibly a gain stage to recover lost gain from the reverb. Next it goes to the phase inverter (which also produces significant gain) and then to the power tubes. Any of these stages could add to the audible distortion.

The basic AB763 circuit is the same on every amp from the Deluxe to the Showman. Same circuit.

BUT there are other factors which influence gain. The Deluxe Reverb runs with significantly lower voltages on the plates of the preamp tubes than say, a Super or a Twin - nearly a hundred volts lower. This reduces the signal each stage can handle before distortion. Furthermore, the choices of value for the cathode resistors and cathode bypass capacitors is important.

So there are a lot of variables for a basic blackface Fender amp. High-gain amps like Soldano or Diesel have many gain stages, each tuned to give a particular gain structure and frequency response.

So there's no simple answer to your question.

steven

freaksho
08-15-2011, 01:41 PM
^ cool.

L_Totti
08-15-2011, 01:45 PM
No, I am not power tubes!

:rimshot

Whalestone
08-15-2011, 02:15 PM
Next it goes to the phase inverter (which also produces significant gain)

I want to add that I believe the phase inverter in the 5E3 (mentioned by freaksho) has a gain of slightly less than unity.

Blues Lyne
08-15-2011, 02:25 PM
yeah, ok. i see. but only if there is a good amount of headroom left in the preamp, no? if otth the amp is set right on the edge of breakup then that 5dB would probably push it into saturation, no? would that grit still be heard even if you turn down the amp?

this is a question i've always wondered: which stages are controlled by the volume knob on nmv amps, and which tubes distort when breakup starts - all of them equally? i have one nmv amp (5E3) and i know i get breakup much earlier on the volume knob when i use an HB guitar than SC, so i use the low input to reduce the signal to the preamp. now what i can't tell is whether the breakup still occurs at the same actual volume once i turn it up from there (hard to tell without a sound level meter or something).

Which tube or tubes distort when breakup starts is very amp dependent. Generally it is tubes toward the end of the chain, often the PI tube. Each gain stage adds some gain (then again there is often attenuation of gain in places between gain stages), so a simplistic picture is to think of each tube stage turning the volume of the signal up a bit. The signal is louder towards the end, so will start pushing those tubes into saturation first. As you turn up the volume, earlier stages will start to saturate also. It's possible for amp designers to design where they want the break up to begin.

The volume control is usually at the beginning, after a gain stage or two, and the master volume is usually right before, or right after the PI tube. So as you turn up the volume and down the MV, you can start to push the stages in between into saturation. Anything after the MV, PI (maybe), power tubes and transformers won't be pushed any harder than they would at a comparable volume without the MV turned down. So say you are running your amp on 3 and it's nice and clean, then you turn up the volume and down the MV until you get dirt, but set it so the volume is the same as it was on 3. Everything from the MV on is essentially still running as it would with the volume on 3.

If you use the boost to overdrive the first stages of the amp, you have essentially set up a scenario similar to the volume/MV set up. The output control on the boost pedal becomes the volume and the volume knob on the amp becomes the master volume. Just like with the volume/mv, anything after the second control will only be pushed as hard as it would when running the amp at the same volume (not volume knob setting) without the boost. A difference between the boost/volume and volume/mv set up is that you generally have fewer gain stages to push into saturation using the boost, and pushing one stage into a lot of dirt tends to sound and react different than having several stages each adding some dirt. The other difference is that, unless you have very high output pickups (amp sound dirty regardless of volume settings), you generally aren't saturating that first stage in any "amp only" situation, the dirt would occur further down the line.

Both the boost/volume and volume/mv set ups sound different than an amp that is turned up loud to get distortion, because both of these methods tend to take power tube and transformer saturation out of the picture, assuming the volume is compensated for. This isn't necessarily bad. You can tend to get tighter distortion with more punch or power. Now, take a smaller amp that is on the verge of break up and hit it with a boost to drive it harder (without turning the volume down) and you will more dirt with all the goodies that power tube and transformer saturation add.

Blues Lyne
08-15-2011, 02:36 PM
Also, as mentioned before, you can use a boost to give you a stronger input signal for gain staging. Kind of like getting the maximum level going into the amp, without distorting the first gain stages. This is similar to the way you would use the gain knob on a mixing console to get the optimum signal level going into the channel.

Dave Barber made a post explaining how to do this with a Launch Pad. Hopefully he's OK with re-posting it here.

How To Cook a Tube Amp-

Here is a tone recipe that works well with most tube amps, this will help improve both clean and overdriven tones and is just in time for the season...your family and friends will love it!

You will need a Barber Launch Pad or other extremely high headroom and uncolored clean boost and a tube amp that has a preamp tube right after the input (nearly all tube amps work this way).

In this case we are going to use the LP as a input trim (ala mixing desk) or as a "tube cooker" to get the most out of your guitars output and maximize gain staging at the input. Plug in your effects chain as normal, with the exception of placing the LP last in the chain. Set the LP Vol + on maximum, set your amp to a fairly low volume clean sound (as in "dead clean") , now footswitch your LP to "on" and start playing clean rhythm on your guitar, use your ear to set the sensitivity of your LP as you play, the idea here is to listen for the amp starting to break up as you are playing your standard rhythm style, when you find the "break up point" back off slightly on the sensitivity until you have the desired clean sound.

Congratulations, you have just set your guitars output for maximized gain staging with your amplifier. After you have the first preamp tube better matched to your guitar, you will need to set your amps volume control a bit lower in most cases and simply set any other effects that come before your LP to their unity gain output position. If your amp has a bright cap permanently attached (deluxe reverb), you could experience some extra top end because of your relatively lower volume settings, the best option here is to “clip out” that offensive bright cap, and most amps will have a bright switch which means you can simply turn that cap off.

Happy Holidays

Enjoy!

freaksho
08-15-2011, 02:54 PM
Which tube or tubes distort when breakup starts is very amp dependent. Generally it is tubes toward the end of the chain, often the PI tube. Each gain stage adds some gain (then again there is often attenuation of gain in places between gain stages), so a simplistic picture is to think of each tube stage turning the volume of the signal up a bit. The signal is louder towards the end, so will start pushing those tubes into saturation first. As you turn up the volume, earlier stages will start to saturate also. It's possible for amp designers to design where they want the break up to begin.

. . .

:jo duh, of course. they are gain stages, afterall. i wasn't thinking.

and a lot of other great info too. thanks for these posts!

hustist1
08-15-2011, 02:59 PM
I want to add that I believe the phase inverter in the 5E3 (mentioned by freaksho) has a gain of slightly less than unity.
Right, it's a cathodyne phase inverter. The blackfaces have a long tail phase inverter. But the combination of gain stage/cathodyne inverter can produce as much gain as a LTPI. And since the 5e3 has a simple tone control, which is low-loss compared to the stack in, say, a BF, not much gain gets lost in that amp.

The 5e3 is the fender gain monster.

steven

johnh
08-15-2011, 03:08 PM
I really hope that the sound with the boost pedal is very, very similar to the sound of the amp turned up - that's the whole point for me. But running with a boost pedal enables me to get the same sound with the boost on and my guitar volume reduced to about 6 or 7, as straight to the amp at full. This way, I get the same great rhythm sound, plus the ability to take solos just by rolling my volume up.

My amp cleans up much, much better with a clean boost pushing it.

sdd17
08-15-2011, 11:00 PM
I really hope that the sound with the boost pedal is very, very similar to the sound of the amp turned up - that's the whole point for me. But running with a boost pedal enables me to get the same sound with the boost on and my guitar volume reduced to about 6 or 7, as straight to the amp at full. This way, I get the same great rhythm sound, plus the ability to take solos just by rolling my volume up.

My amp cleans up much, much better with a clean boost pushing it.

Why wouldn't just turning your amp up while still backing off your guitar volume achieve the same effect?

Gearopenia
08-15-2011, 11:06 PM
I use boosts for the way they seem to color the sound.
Makes it more robust.
Always have the EP boost on with single coils, the supratrem on as a boost with humbuckers. The mix Klon, KOT, or tim for the level of drive I want.
Works for me

mmolteratx
08-15-2011, 11:43 PM
That blanket statement is way to simplistic for a huge variety of amps out there. There's post phase inverter master volumes, output transformer sagging, VVR power scaling, attenuators, etc, etc, etc... A lot of this stuff happens in the best amps out there, too.

What. This is the same volume for the same amp with out any attenuators or other crap. Of course if you use voltage reduction and attenuators all of that gets thrown out the window. Without any other changes, your power tubes are amplifying what they see at the grid by the same amount until driven into saturation or cut off.

No, I am not power tubes!

:facepalm:

And usually I even check to make sure there are no grammar mistakes.

hustist1
08-16-2011, 10:33 AM
What. This is the same volume for the same amp with out any attenuators or other crap. Of course if you use voltage reduction and attenuators all of that gets thrown out the window. Without any other changes, your power tubes are amplifying what they see at the grid by the same amount until driven into saturation or cut off.


No.

IT IS POSSIBLE TO OVERDRIVE THE INPUT GRID OF A TUBE. Overdriving the input grid of a tube will NOT result in a greater voltage swing at the plate - so the following stage would SEE THE SAME (maximum) AMOUNT OF SIGNAL. The maximum voltage swing of a stage is set by the B+ voltage, the plate resistor, and the bias point of the tube. There is a hard maximum for any specific, real-world gain stage which cannot be exceeded no matter how many gadzillions of volts you swing the grid. But since you are driving the grid to current limiting or cutoff, the tone will be different, because the characteristics of the distortion are different. The harder you overdrive the grid, the stronger the distortion, but the voltage swing at the plate - which is the input to the next stage - won't change. The shape of the signal waveform changes, but not the amplitude.

Furthermore, distortion from a voltage gain stage has a different characteristic than distortion from a cathode follower stage, a phase inverter stage (of any type), or driving the output tubes to saturation.

Finally, driving the speaker hard has an important effect on the distortion.

So really, to get authentic cranked-amp tone at low volumes, you need a very inefficient speaker driven near its limits. This is the idea behind the new Eminence speakers with the adjustment on the back. Though I've never tried one and don't know how well they work.

If you want an overview of gain stages, read this:

http://www.freewebs.com/valvewizard1/Common_Gain_Stage.pdf

steven

mmolteratx
08-16-2011, 12:58 PM
I'm talking before the power section starts distorting. Of course it compresses once it starts distorting. I'd say I know just a little bit about tube amps. ;)

sanhozay
08-16-2011, 01:12 PM
good thread. smart people with great comments. me likey.